1. Field of the Invention
The present invention generally relates to apparatus and methods for completing a well. Particularly, the present invention relates to a retractable joint and/or a cementing shoe for use with conventional well completions and with drilling with casing applications.
2. Description of the Related Art
In the oil and gas producing industry, the process of cementing casing into the wellbore of an oil or gas well generally comprises several steps. For example, a section of a hole or wellbore is drilled with a drill bit which is slightly larger than the outside diameter of the casing which will be run into the well. Next, a string of casing is run into the wellbore to the required depth where the casing lands in and is supported by a well head.
Next, cement slurry is pumped into the casing to fill the annulus between the casing and the wellbore. The cement serves to secure the casing in position and prevent migration of fluids and gasses between formations through which the casing has passed. Once the cement hardens, a smaller drill bit is used to drill through the cement in the shoe joint and further into the formation.
Typically, when the casing string is suspended in a subsea casing hanger, the length of the casing string is shorter than the drilled open hole section, allowing the casing hanger to land into the wellhead prior to reaching the bottom of the open hole. Should the casing reach the bottom of the hole prior to landing the casing hanger, the casing hanger would fail to seal and the casing would have to be retrieved or remedial action taken.
In some instances, the area between the end of the casing (sometimes called the “shoe”) and the end of the drilled open hole can become eroded to an even larger diameter than the original open hole. A typical cementing operation fills the volume between the annulus and casing above the shoe with cement, but not the section below the shoe. When the next section of open hole is drilled and casing is run, this increased diameter below the previous casing string allows mud circulation velocity to decrease, leaving debris and cuttings in this hole. The debris and cuttings can lead to pack off problems and trouble logging the well.
One prior art solution is disclosed in U.S. Pat. No. 5,566,772 (Coone, et al., issued Oct. 22, 1996). This solution uses pressurized fluid to extend a tubular member to the bottom of the open hole section once the casing has been landed. Pressure and/or circulation is required to activate the system. In one embodiment, a plug must be dropped from the surface to seal the bore of the casing shoe. This wastes valuable rig time. If the plug is dropped prior to landing the casing, the potential exists to set the shoe prematurely or restrict circulation. In formations where this enlarged section exists, activating and extending the shoe with pressure is likely to surge and damage the formation leading to other problems such as loss of drilling fluid and cement into the formation.
Therefore, there exists a need in the art for an improved method and/or apparatus for completing a subsea wellbore.